Draw adjacent paths in onroad UI

Added toggle to draw the adjacent paths in the onroad UI to visualize what other lanes the model sees.

selfdrive/ui/qt/onroad.h

@@ -134,6 +134,8 @@ private:
   bool turnSignalRight;
 
   float distanceConversion;
+  float laneWidthLeft;
+  float laneWidthRight;
   float speedConversion;
 
   int cameraView;